How to reset your Custom Post Type UI settings
If you wish to start fresh and remove all current post type or taxonomy settings, there are a few ways to do so.
None of the provided methods will delete the content created with the post types or taxonomies, just the settings used to register them. If you want to delete the content as well, do so via the appropriate WordPress screens for each.
Manually delete each registered item
The first way would be through the edit tab for both post types and taxonomies. Simply select each one and use the provided delete button.
Delete directly from database tables
When it comes to CPTUI specific settings, we use two different rows in the wp_options table.
Your prefix may be different than "wp_". If you are not sure what yours is, check your wp-config.php file.
In the options table, look for rows with an option key of either
and manually delete them.
Would be advisable to back up your database first just in case.
Delete from the Import/Export page
If you do not want to manually go through each post type and taxonomy, and are not comfortable editing the database tables directly, there is one last way you could clear out the settings.
If you visit the Import/Export page and import the following, it will also clear out your saved options:
The double quotes are important to make this successful. Single quotes will report an import failure.
Essentially what this does is import an empty value, and clear out the previous values.